CCST Project

Fumigant Use in California and an Assessment of Available Alternatives

Overview

Responding to a request from the California Department of Pesticide Regulation (DPR), CCST conducted a review of current fumigant use in California and a comprehensive assessment of available alternatives to these fumigants. Broadly, a fumigant is a volatile or volatilizable chemical compound used as a pesticide. Fumigants can be used as an insecticide, fungicide, disinfectant, nematicide, herbicide, and even a rodenticide. They can be applied in a wide variety of settings such as in the home, in structures, healthcare and food facilities, for crop growth and management, and to control vector-borne or animal-borne diseases.

Phases and Scope

Across two phases, the study assessed:

The present state of fumigant use in California (including ways to mitigate emissions for post-harvest applications)
Currently available alternatives for these fumigants and the extent of their use
Past and on-going research dedicated to fumigant alternatives
Viability of adopting these alternatives to effectively manage pests in California
Barriers to wide-scale adoption of alternatives
Areas where research may still be needed to answer some of these questions

Although fumigants are used in a variety of settings, the study focused on three uses of fumigants: pre-plant soil fumigation, post-harvest commodity fumigation, and structural fumigation.

Fumigants covered in the study were limited to:

Agricultural pre-plant soil fumigants
- 1,3-dichloropropene (1,3-D)
- Chloropicrin
- Dazomet
- Metam-Sodium
- Potassium N-Methyldithiocarbamate (Metam-potassium)
- Methyl bromide

Post-harvest commodity fumigants
- Sulfuryl Fluoride
- Phosphine
- Propylene oxide
- Methyl bromide

Structural fumigants
- Sulfuryl Fluoride

CCST conducted this study across two phases. The Phase I report, completed in February 2025, focuses exclusively on the pre-plant soil fumigants 1,3-D and chloropicrin and their alternatives.

The Phase II report, published February 2026, has an expanded scope that includes the four remaining pre-plant soil fumigants as well as the fumigants used for treating post-harvest commodities and structures. The final report, published July 2026, focused on pre-plant fumigants, specifically methyl bromide and three pesticides known as MITC generators: dazomet, metam-sodium, and metam-potassium.